An oil or gas well are normally built up by a number of steel casings in various sizes, with the largest diameter closest to the surface, and thereafter smaller sizes with increasing depth of the well, to the final production casing through the reservoir. Especially during injection of steam, the thermal expansion of the casing can over time cause large damages to the cemented casing that can reduce the production capacity of the well. In heavy oil applications, steam is often used to reduce the viscosity of the heavy oil by increasing the temperature on the reservoir/oil, to increase production.
During the process of completing an oil well for hydrocarbon production or injection purposes, a casing string will be run into the well bore. The casing is fabricated in sections, or joints, that are usually about 40 feet long and screwed together to form longer lengths of casings, called casing strings. Each end of the casing section has male (pin) threads and is connected by using a collar or coupling, composed of a short cylindrical steel pipe that is slightly larger in diameter than the casing sections and also has female (box) threads. The casing is run from the rig floor, connecting one section at the time by casing elevators on the travelling block and stabbed into the previous casing string that has been inserted into the well. Hanging above the drill floor, casing tongs screw each casing section to the casing string. After installation, the casing is cemented in place by pumping cement slurry through the inside of the casing and out into the annulus through the casing shoe at the bottom of the casing string. Once the casing has been run in the well, and cemented, it may be perforated to allow injection or production condition to occur. High temperatures and pressures can occur during this process which will affect the normal properties of the steel material in the casing. A problem with casing strings according to prior art, especially in the case of steam injection, is that the thermal expansion of the casing can cause different types of irreparable damages to the casing that will influence the production capacity of the casing. Consequently, there is a need for a well with a casing string which provides a continuous production capacity and which can be used at a low maintenance cost. There is also desired a casing string which is prevented from deforming due to thermal expansion or tensile forces. There is also desired a casing string in which axial forces and rotating torques are allowed to be transferred through the casing string during installation.